When I did my 55g to my 125g I started with all new sand. I put in thenew sand, added the saltwater and then setup the sump. I let it run a few days to get any clouding down, which luckily I didnt have much of.
I then moved the majority of my rock over and left some in with the fishies. After a few more days I did the big move with the rest of the live rock and the extra base rock I had ordered. I left a little of the water in the 55g and slowly caught my fish, acclimated them and in they went.
I did have a 3 day ammonia spike though between initial filling with the majority of the live rock and the refugium contents that came from my pod tank I had cgoing. thats why I let the fish stay in the 55g without much rock, to wait out the ammonia.
It took me several hours to get everything moved over but it wasnt too traumatic and I did pretty well.
At least til I added new fish a week or two later and it all went downhill. But thats another issue. Maybe my tank wasnt ready for the new additions so soon after the move or most likely one of the fish I added had an issue. I was not qt'ing then.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.